In the latest PTR, the Hellfire Ring recipe from Squirt in Act II is the old version whose materials are no longer available in the game. In previous seasons there were two, the old one and the one which required the Uber Bosses materials from the various realms. The version which we can obtain the materials for is not an option in this PTR. This apears as though someone tried to remove the old version, but removed the wrong one.
She has always sold that recipe, she sells the level 70 version as well though, both on live and on the PTR.
The Diablo III (without Reaper of Souls) version of the Hellfire Ring Design costs 2 million Gold from Squirt.
If you have Diablo III: Reaper of Souls you want to avoid the 2mil Design and purchase the 5 million Gold Hellfire Ring Design instead. (As @Kargon mentioned).
That’s not true, if you have Diablo III without Reaper of Souls. There’s also a way to get the older Mats, in Reaper of Souls, at Character Level 60. But, there’s a trick to it and I’m not sure it’s worth it.
In any event: This is NOT a bug.